It is known in the art to generate EUV light from the production of a plasma of an EUV source material which plasma may be created by a laser beam irradiating the target material at a plasma initiation site (i.e., Laser Produced Plasma, “LPP”) or may be created by a discharge between electrodes forming a plasma, e.g., at a plasma focus or plasma pinch site (i.e., Discharge Produced Plasma “DPP”) and with a target material delivered to such a site at the time of the discharge. Target delivery in the form of droplets of plasma source material, which may, e.g., be mass limited for better plasma generation conversion efficiency and lower debris formation, are known techniques for placing the plasma source material at the appropriate location and at the appropriate time for the formation of the plasma either by LPP or DPP. A number of problems are known to exist in the art regarding the handling of the target material, e.g., liquid metal feeding to a mechanism for the formation of target droplets either of the metal itself or a suspension, dispersion or other mixture of the target material with a liquid that is not reactive with the target material, e.g., water or alcohol for a tin metal plasma source material and a liquid plasma source material compound such as Li(CH3). The present applications relates to aspects of embodiments of methods and apparatus for dealing with such problems.
Complex liquid metal handling systems are found in certain liquid metal cooled nuclear reactors, as wall protection in experimental fusion reactors and for use with targets in high energy particle accelerators.